class_docstr: DAGRepr test
class_docstr_tok: ["DAGRepr","test"]
code: def test_check_input(self):
      towhee_dag_test = copy.deepcopy(self.dag_dict)
      towhee_dag_test.pop("_input")
      with self.assertRaises(ValueError):
          DAGRepr.from_dict(towhee_dag_test)
  
file_path: towhee/tests/unittests/runtime/test_dag_repr.py
imports: import copy
  import unittest
  from towhee import pipe
  from towhee.runtime.dag_repr import DAGRepr, NodeRepr
  from towhee.runtime.data_queue import ColumnType
  from towhee.runtime.schema_repr import SchemaRepr
label_desc: Use image node_id 2 for calling the TestDAGRepr obj's underlying member method code with example usage: obj.test_check_input() without return types